1. Field of the Invention
The present invention relates to a radiotherapy apparatus. More particularly, the invention is directed to a radiotherapy apparatus, which can be controlled based on a radiotherapy plan made by referring to a CT image obtained from an integrally provided CT device.
2. Description of the Related Art
With regard to currently practiced radiotherapy, a treatment is generally carried out by operating the CT device, a therapy planning device, a patient positioning device including a bed, and a radioactive ray irradiating device in linkage. Specifically, the CT device is used to form a CT image regarding the affected part of a patient by picking up the image thereof; the therapy planning device to create setting information for each device involved in radioactive ray irradiation according to each case by referring to a three-dimensional image obtained from the CT device; and the radioactive ray irradiating device to treat a disease, such as a tumor or the like, present in the body of the patient by irradiating a diseased part with radioactive rays, e.g., X-rays or electron beams. Usually, the combination of the patient positioning device and the radioactive ray irradiating device is referred to as a radiotherapy apparatus.
Conventionally, the CT device and the radioactive ray irradiating device have been installed in places away from each other, and separately operated. However, for the purpose of enhancing operability and therapy performance by increasing linkage among the devices involved in radiotherapy, and reducing overall costs, requests have been made to integrate such devices. To meet these demands, efforts have been made to develop an apparatus, which includes, for example, a linear acceleration CT disclosed in Japanese Patent Application Laid-Open No. 1984-000076, and a tomographic therapy device disclosed in U.S. Pat. No. 5548627.
FIG. 6 is a schematic sectional view of the constitution of the above-noted tomographic therapy device, specifically showing a case where the portion of a device main body is seen from the foot or head side of a patient. In FIG. 6, a reference numeral 10.1 denotes a patient to be treated; 102 an affected part of the patient 101; 103 a bed for the patient 101; 104 an X-ray source for CT; 105 an X-ray beam for CT, radiating from the CT X-ray source 104; 106 an X-ray detector for CT; 107 a radioactive ray source for therapy; 108 a collimator; and 109 a radiation beam for therapy, radiating from the therapy radioactive ray source 107. The CT X-ray source 104, the CT X-ray detector 106, the therapy radioactive ray source 107 and the collimator 108 are mounted on the same endless rotating mechanism. A reference numeral 110 denotes a geometrical center axis. The CT X-ray source 104 and the therapy radioactive ray source 107 are secured to the endless rotating mechanism in such a way as to be separated from each other by 90xc2x0 seen from the center axis 110. A reference numeral 111 denotes an inner wall portion inhibited from being rotated; 112 an outer wall portion similarly inhibited from being rotated; and 113 a device main body including the bed 103, the CT X-ray source 104, the CT X-ray detector 106, the therapy radioactive ray source 107, the collimator 108, the inner and outer wall portions 111 and 112, and other members, not shown. A reference numeral 114 denotes an image processing computer for forming a CT image regarding an affected part or the like, and creating control information regarding the device main body 113 by referring to the CT image; and 115 a therapy control computer for controlling each device involved in the execution of radiotherapy based on the control information. Interconnections are made between the computers, and between the computers and the above devices by a not-shown network, and information is transferred around by an analog or digital signal.
Now, the typical structures of a radiotherapy apparatus and a CT device developed and made available in the conventional art are described. The radiotherapy apparatus is constructed in such a manner that a gantry head as a beam radiation portion is provided in a gantry installed as an arm-shaped supporting frame, and this gantry is mounted on a rotating mechanism provided in a device main body fixed in a therapy room. The CT device is constructed in such a manner that inside a cylindrical image pickup device, into which a bed carrying a patient can be inserted, an X-ray tube and an X-ray detector are provided symmetrically to the center axis of the cylindrical body, and a rotating mechanism is provided in a device main body for rotating the cylindrical body around the patient. The X-ray detector provided in the CT device comprises a row of detecting elements disposed in an arc shape, and can pick up the image of one section by one rotation. The parallel arrangement of such a plurality of detecting elements also enables multi-slicing to be realized, which simultaneously picks up a plurality of sections by one rotation.
Next, the operation of the tomographic therapy device shown in FIG. 6 is described.
After the patient 101 is secured to the bed 103, X-rays radiate from the CT X-ray source 104 while the endless rotating mechanism is rotated. Then, by using the CT X-ray detector 106 to detect the X-rays passed through the patient 101, image pickup data is obtained regarding one section of the affected part of the patient 101. The image processing computer 114 receives a signal regarding the image pickup data outputted from the CT X-ray detector 106, and forms a CT image of the affected part for each rotation of the endless rotating mechanism. When necessary, this process is repeated to form a three-dimensional image. Then, based on the formed CT image, the image processing computer 114 creates control information to generate a therapy radiation beam 109 necessary for realizing proper radiotherapy. In the described tomographic therapy device, the therapy radiation beam 109 is generated while the endless rotating mechanism is rotated as in the case of CT photographing. Accordingly, control information is created in such a way as to optimize setting regarding the opening state or the like of the collimator 108 for each position on a rotational path of the therapy radioactive ray source 107.
The control information thus created is then sent as therapy plan information to the therapy control computer 115. Based on the provided therapy plan, and according to the rotation of the endless rotating mechanism, the therapy control computer 115 executes radiotherapy by converging radioactive rays radiating from the therapy radioactive ray source 107, by the collimator 108, to match the shape of the patient 101. When the endless rotating mechanism disposed between these wall portions or each device mounted on the endless rotating mechanism is rotated, the presence of the inner and outer wall portions 111 and 112 can prevent the clashing of such a rotating object with the patient 101, the bed 103 or other external objects.
However, some problems have been inherent in the foregoing constitution of the tomographic therapy device made available as the radiotherapy apparatus in the conventional art. Specifically, the integrated arrangement of the CT device and the radioactive ray irradiating device on the same endless rotating mechanism has resulted in the increases in weight and volume of the rotating mechanism, creating the mechanical difficulty of achieving high-speed rotation necessary for the CT device.
To rotate the radioactive ray irradiating device at a high speed as in the case of the CT device, it is essential to achieve high-speed control at the radioactive irradiating device side. Particularly in the case of the collimator for mechanically controlling a field of irradiation, there has been a difficulty of changing each setting at a high speed according to a rotational angle.
Furthermore, since the therapy radioactive ray source generally uses a large-output high frequency, the mounting thereof with the CT device on the same endless rotating mechanism itself has been technically difficult.
The present invention has been made to solve the foregoing problems, and it is an object of the invention to provide a radiotherapy apparatus comprising a radioactive ray irradiating device and a CT device provided in one device, and capable of guaranteeing desired operational characteristics required of the radioactive ray irradiating device and the CT device.
A radiotherapy apparatus provided by the invention comprises: a bed, a position thereof being adjustable; an X-ray source for CT; an X-ray detector for CT; a CT rotating mechanism for supporting the CT X-ray source and the CT X-ray detector rotatably around the bed; a radioactive ray source for irradiating radioactive rays for therapy; a collimator provided for converging a shape of a therapy radiation beam radiating from the radioactive ray source; and a therapy rotating mechanism for supporting the radioactive ray source and the collimator rotatably around the bed independently of the CT rotating mechanism.
The radiotherapy apparatus of the invention further comprises: correction amount computing means for computing deviation in a position or a direction of an affected part by comparing a CT image obtained by photographing carried out by using a CT device composed of a CT X-ray source and a CT X-ray detector, and referred to when a therapy plan is made, with a CT image obtained by photographing carried out by using the CT device immediately before radiotherapy.
The radiotherapy apparatus of the invention further comprises: radioactive ray irradiation control means for performing control to detect a relative angle difference between the therapy rotating mechanism and the CT rotating mechanism, and stop irradiation of radioactive rays from the radioactive ray source in a range of angles, interference occurring in therapy radioactive rays therein.
In the radiotherapy apparatus of the invention, affected part information recording means is provided for recording time and space information regarding an affected part currently subjected to radiotherapy, obtained by executing CT photographing simultaneously with the radiotherapy.
The radiotherapy apparatus of the invention further comprises: image processing means for forming a CT image regarding an affected part or the like, and transmitting data of the CT image through a network; and therapy control means for receiving an entry of therapy plan information through the network, and controlling each device involved in execution of radiotherapy based on the therapy plan information.
The radiotherapy apparatus of the invention further comprises: affected part position detecting means for detecting an affected part position in real time.
The radiotherapy apparatus of the invention further comprises: affected part shape detecting means for detecting an affected part shape in real time.